Various techniques for increasing speech call quality in a terminal such as a mobile phone or a tablet PC have been developed. For example, quality of a speech signal to be provided from a transmission end may be enhanced through pre-processing. Specifically, speech quality may be enhanced by detecting the characteristics of ambient noise to remove noise from the speech signal to be provided from the transmission end. As another example, speech quality may be enhanced by equalizing, in consideration of the characteristics of the ears of a terminal user, a speech signal restored by a reception end. As another example, enhanced speech quality of the restored speech signal may be provided by preparing a plurality of pre-sets in consideration of the general characteristics of the ears to the reception end and allowing the terminal user to select and use one thereof.
In addition, speech quality may be enhanced by extending a frequency bandwidth of a codec used for a call in the terminal, and particularly, a technique of extending a bandwidth without changing a configuration of a standardized codec has been required.